Black matrix on array (BOA) technique is a popular technique for manufacturing a liquid crystal display (LCD) panel. In a BOA process, a color filter (CF) substrate is not used, which renders a CF process unnecessary and can reduce costs, improve the alignment precision of the manufacturing process, and is conducive to manufacture of display devices of high aperture ratio and high resolution.
In a traditional BOA process, a black matrix (BM) is an organic photoresist, and patterning is performed after coating of R/G/B color resist. Since the BM has a high requirement for optical density, but the optical density of the existing BM for a BOA structure is low, a coating of the BM is extremely thick. However, the thick BM coating can shield alignment marks on the array substrate, which is not conducive to exposure alignment in the process. Further, for a BM with large height, it is difficult to control a taper angle thereof and the taper angle is relatively steep, which may cause breakage of pixel indium tin oxide (ITO; ITO is an N-type oxide semiconductor, and ITO thin film is indium tin oxide semiconductor transparent conductive film) when ITO laps on the BM.
Metal oxides have good insulativity. However, many metal oxides, especially those materials that are widely used in industrial applications, such as aluminum oxide (Al2O3), have good transmissivity, and are not suitable for use as a BM material. The inventors of the present disclosure found that copper oxide (CuO) as a black oxide is easily used in industrial production and can be used as a BM material.
IGZO (indium gallium zinc oxide, a metal oxide) is a good material for an active layer of a thin film transistor (TFT) because of its high mobility, good film formation uniformity, easiness in large-size production, and because it can be applied in the same manufacturing process as arsenic (As). In recent years, IGZO has been widely developed. Similar to ITO, IGZO is easy to be etched by aluminum hydroxide (Al(OH)3), so it is generally not suitable for use as a component with a back channel etched (BCE) structure. This is because, in a BCE structure, an IGZO layer is etched away when a source and a drain are formed by etching, which can result in failure in the manufacture of the TFT component.
In view of the foregoing, the inventors of the present disclosure designed a BOA liquid crystal panel based on an IGZO-TFT and a method for manufacturing the same to eliminate the above-mentioned defect.